1. Field of the Disclosure
The present invention relates to an organic luminescence display panel and a method for fabricating the same which can improve a lifetime and luminous efficiency of an organic luminescence display device.
2. Discussion of the Related Art
A display device, a core technology in a time of information and communication for displaying various pieces of information as pictures, is being developed in a direction of thinner, lighter, portable and high performance. According to this, the organic luminescence display device (OLED) and the like which can reduce weight and volume that are disadvantages of a cathode ray tube (CRT) are spotlighted. The OLED, a light emitting device which uses a thin light emission layer between electrodes, has an advantage of making thin like paper.
An active matrix OLED (AMOLED) has a matrix of pixels each with three colored subpixels of R, G, B for displaying a picture. The subpixel has an organic electro-luminescence (OEL) cell, and a cell driver for driving the OEL cell independently. The cell driver has a gate line for supplying a scan signal, a data line for supplying a video data signal, and at least two thin film transistor and storage capacitors connected between common power lines which supply common power signals, for driving a cathode of the OEL cell. The OEL cell has a cathode connected to the cell driver, an organic layer on the cathode, and an anode on the organic layer. The organic layer has a hole injection layer, a hole transport layer, a light emission layer, an electron injection layer, and an electron transport layer. A lifetime of the OEL cell is limited due to degradation of the OEL cell caused by improper current injection to the OEL cell coming from instable interface between the anode and the hole injection layer, if a current is applied to the OEL cell. In order to correct such an interface instability, a buffer layer is provided between the anode and the hole injection layer for improving the lifetime. However, the buffer layer becomes a barrier to require a higher driving voltage for increasing efficiency of the light emission layer. Moreover, since the hole has a moving speed higher than the electron such that the hole is not trapped at the light emission layer, but moves to the electron transport layer, to impair the efficiency of the light emission layer.